Albert Einstein

Chapter 1 · The Boy with the Compass

Munich, Aarau and a rejected education

1879 – 1900 · Ulm · Munich · Aarau · Zurich

Albert Einstein was born in Ulm on 14 March 1879 into a secular Jewish family; his father ran an electrical equipment business. When he was about five and ill in bed, his father showed him a compass. That the needle was moved by something invisible left an impression he described sixty years later as a deep and lasting wonder that something must lie hidden behind things.

He was not a poor student — the story that he failed mathematics is false, and he had mastered calculus by fifteen. What he could not tolerate was the Munich Gymnasium's authoritarian teaching. He left at fifteen without a diploma, and formally renounced his German citizenship at sixteen, partly to avoid military service, becoming stateless for five years.

He failed the general section of the ETH Zurich entrance examination while scoring outstandingly in mathematics and physics, and was sent to finish school at Aarau in Switzerland, where teaching was liberal and students were encouraged to think visually. It was there, aged sixteen, that he first asked what a light beam would look like if you rode alongside it — a question he returned to for ten years.

At the ETH he skipped lectures, relied on his friend Marcel Grossmann's notes, and irritated his professors. He met Mileva Marić, one of very few women studying physics in Europe. On graduating in 1900 he was the only one of his group not offered an assistantship.

Why this matters

Einstein's thought experiment about riding a light beam, formed at sixteen, is the question special relativity eventually answered — evidence that his physics grew from a decade of stubborn wondering.

You have met the student nobody wanted to employ. What would you ask him?

Ask Einstein

• “What did the compass make you think at five years old?”
• “Why did you leave school in Munich?”
• “What would you see if you rode alongside a beam of light?”
• “Is it true you failed mathematics?”
• “Why did no professor offer you a job?”

Chapter 2 · The Miracle Year

Four papers, written in the evenings, from a patent office

1902 – 1905 · Bern

Unable to find an academic post, Einstein took a job in 1902 as a technical expert third class at the Swiss patent office in Bern, assessing applications — many of them for devices synchronising clocks across railway networks, a fact historians have found suggestive. He worked physics in the evenings and during quiet hours, and with friends formed a reading group they jokingly called the Olympia Academy.

In 1905, aged twenty-six, he published four papers.

The first proposed that light behaves as discrete quanta of energy, explaining the photoelectric effect — why light knocks electrons out of metal in a way depending on frequency, not brightness. This was the paper that won him the Nobel Prize, and it helped found quantum theory.

The second explained Brownian motion, the jittering of pollen grains in water, as the statistical result of collisions with molecules — providing strong evidence that atoms are real, which was still disputed.

The third introduced special relativity, built on two postulates: the laws of physics are the same for all observers moving at constant velocity, and the speed of light in a vacuum is the same for everyone regardless of their motion. Accepting both forces the conclusion that time and distance are not absolute. Moving clocks run slow; simultaneity depends on the observer.

The fourth, a three-page afterthought, derived the equivalence of mass and energy — the relation written as E = mc².

His wife Mileva Marić checked his mathematics and discussed the work with him; how much she contributed is debated and the evidence does not settle it.

Why this matters

1905 is the most productive year any physicist has had: two of the four papers founded quantum theory and relativity, the two pillars of twentieth-century physics.

You have four papers in one year. What would you ask him?

Ask Einstein

• “How did the patent office help rather than hinder your physics?”
• “Why does the speed of light being constant break time?”
• “What does E = mc² actually mean?”
• “How did Brownian motion prove atoms exist?”
• “What part did Mileva Marić play in your work?”

Chapter 3 · Curved Space and an Eclipse

The happiest thought, and eight years of mathematics

1907 – 1919 · Bern · Prague · Berlin · Príncipe

In 1907 Einstein had what he called the happiest thought of his life: a person falling freely does not feel their own weight. From that he drew the equivalence principle — that gravity and acceleration are locally indistinguishable — and spent eight years turning it into a theory.

The mathematics nearly defeated him, and Marcel Grossmann taught him the non-Euclidean geometry he needed. The result, presented in November 1915, replaced gravity as a force with gravity as geometry: mass and energy curve spacetime, and objects follow the straightest available paths through that curvature. The Moon is not pulled by the Earth; it follows a straight line through curved space.

The theory made testable predictions. It accounted exactly for a long-standing anomaly in Mercury's orbit that Newton's mechanics could not explain. And it predicted that starlight passing close to the Sun would bend by twice the amount Newtonian physics implied.

In May 1919, expeditions organised by Arthur Eddington photographed stars near the eclipsed Sun from Príncipe off West Africa and from Brazil. The measured deflection matched Einstein. The announcement in London that November made front pages worldwide — a German physicist's theory confirmed by British astronomers a year after the war.

Einstein was famous overnight in a way no scientist had been before. He received the Nobel Prize in 1921, awarded for the photoelectric effect rather than relativity, which the committee still considered insufficiently settled.

“The most incomprehensible thing about the world is that it is comprehensible.”

— Albert Einstein, 'Physics and Reality', Journal of the Franklin Institute, 1936

Why this matters

General relativity underpins modern cosmology, black holes and gravitational-wave astronomy, and satellite navigation systems must correct for it to give accurate positions.

You have gravity as geometry. What would you ask him?

Ask Einstein

• “What was the happiest thought of your life?”
• “How can gravity be the shape of space rather than a force?”
• “Why did Mercury's orbit matter so much?”
• “What would you have done if the eclipse results had disagreed?”
• “Why was your Nobel Prize not for relativity?”

Chapter 4 · God Does Not Play Dice

Losing the argument, and being useful in defeat

1925 – 1935 · Berlin · Brussels · Princeton

Einstein had helped start quantum theory and could not accept where it went. By the late 1920s Bohr, Heisenberg and others had built a quantum mechanics in which the fundamental description of a particle is a probability, and in which measurement outcomes are irreducibly random.

Einstein objected that this could not be the complete story. In a 1926 letter to Max Born he wrote that quantum theory produced a good deal but hardly brought us closer to the secret of the Old One — and that he was convinced He does not play dice. The line is usually quoted more loosely than he wrote it.

At the Solvay Conferences of 1927 and 1930 he arrived each morning with a thought experiment designed to defeat the uncertainty principle, and Bohr generally answered it by evening — on one famous occasion by using Einstein's own general relativity against him.

In 1935, with Podolsky and Rosen, he published the EPR paper, arguing that quantum mechanics implied two separated particles could instantaneously share a state, which he considered a 'spooky action at a distance' and therefore a sign the theory was incomplete.

He was, on the evidence, wrong. From the 1960s John Bell turned the EPR argument into a testable inequality, and experiments from the 1970s onward — recognised with the 2022 Nobel Prize — showed that nature really does behave as quantum mechanics predicts. But the objection was so precisely formulated that it became the foundation of quantum entanglement research and, ultimately, of quantum computing and cryptography.

It is one of the best examples in science of a wrong argument being enormously productive.

Why this matters

Einstein's failed objection to quantum mechanics generated the concept of entanglement, which is now the basis of quantum computing and quantum cryptography.

You have a great physicist losing an argument. What would you ask him?

Ask Einstein

• “What did you actually mean by God not playing dice?”
• “Why did you find randomness in physics unacceptable?”
• “What was the EPR argument trying to show?”
• “How does it feel to have been proved wrong so productively?”
• “What did Bohr understand that you resisted?”

Chapter 5 · Refugee, Signature, Conscience

Princeton, the bomb, and civil rights

1933 – 1955 and after · Princeton · New Jersey

Einstein was abroad when Hitler took power in 1933 and never returned to Germany. His property was seized, his books burned, and a bounty was placed on his head. He settled at the Institute for Advanced Study in Princeton and became an American citizen in 1940.

In August 1939 the physicist Leó Szilárd drafted a letter to President Roosevelt warning that Germany might build an atomic bomb, and asked Einstein to sign it because his name would be read. He did. It contributed to the process that led to the Manhattan Project. Einstein — a lifelong pacifist who had been denied security clearance and did no work on the bomb — later said that had he known the Germans would fail, he would never have lifted a finger.

His civil rights work is less well known and was substantial. He called racism America's worst disease, joined the NAACP, befriended Paul Robeson and W. E. B. Du Bois, and in 1946 travelled to Lincoln University, a historically Black institution, to receive an honorary degree and give a lecture on relativity to the students — at a time when few white academics would appear at such a place.

Offered the presidency of Israel in 1952, he declined, saying he lacked both the aptitude and the experience to deal properly with people.

His last decades were spent on a unified field theory joining gravity and electromagnetism. He never succeeded, and most physicists thought he was wasting his time on the wrong problem with the wrong tools — though unification remains an open goal.

He died on 18 April 1955 of a ruptured aortic aneurysm, refusing surgery. The pathologist removed his brain without family permission, an episode that remains an ethical scandal.

Why this matters

Einstein's public life established a model of the scientist as a moral voice — on war, on nuclear weapons and on racism — which shaped what people expect scientists to speak about.

You have the conscience as well as the physics. What would you ask him?

Ask Einstein

• “Why did you sign the letter to Roosevelt?”
• “Why did you call racism America's worst disease?”
• “Why did you refuse the presidency of Israel?”
• “Were your last thirty years on unification wasted?”
• “What should a scientist do when their work becomes a weapon?”

What Einstein changed

Einstein's special and general relativity replaced Newton's absolute space and time, and remain the foundation of cosmology, black hole physics and satellite navigation. His work on light quanta helped found quantum theory, and the EPR argument he intended as a criticism became the basis of entanglement research.

A debate that continues

Historians continue to examine the extent of Mileva Marić's contribution to the 1905 papers, and physicists still discuss whether Einstein's rejection of quantum indeterminacy was a failure of imagination or a legitimate demand for a deeper theory.

Keep exploring — ask Einstein

• “How do you know when a thought experiment has told you something real?”
• “What did you most want a unified theory to explain?”
• “Which of your own ideas surprised you most?”

Related lives

• Isaac Newton — Lucasian Professor · President of the Royal Society
• Niels Bohr — Architect of the Quantum Atom
• J. Robert Oppenheimer — Father of the Atomic Bomb

Related themes

Relativity · Quantum physics · Science and moral responsibility